Anticoagulant medicines can interact with a wide range of other medication. In some cases, the interaction will stop the anticoagulant medicine working. In other cases, it will increase the anticoagulant effect.

If you are taking anticoagulants and you start, stop or change the dose of any other kind of medication, speak to your GP, pharmacist or another healthcare professional.

These types of medication include:

• prescription medicines
• medicines bought over the counter without prescription, such as aspirin
• any herbal remedies
• any food or drink supplements

Prescription medicines that can interact with anticoagulants include the following:

• antibiotics 
• non-steroidal anti-inflammatory drugs (NSAIDs) 
• corticosteroids
• oral contraceptives
• selective serotonin reuptake inhibitors (SSRIs; a type of antidepressant medication)

For a full list of medicines that interact with the anticoagulant you are taking, see our anticoagulant medicines information pages.

Your prescription should also come with a booklet that may provide this information, or you can ask your pharmacist or GP. If you have any further questions, you can call NHS 111.

Warfarin

Warfarin may not be effective if you take too much vitamin K, either through your diet or in supplements.

The effect of warfarin is increased by alcohol. If you are taking warfarin, do not drink more than one or two alcoholic drinks a day and never binge drink. 

The maximum recommended daily limits for alcohol consumption are three to four units a day for a man and two to three units a day for a woman. One unit of alcohol is approximately half a pint of weak lager or bitter.

Read more about which medicines interact with warfarin.